Influence of Orthodontic Tooth Movement Direction on Periodontal Regeneration Outcomes: A 2-Year Retrospective Study

Introduction and aims To evaluate whether the direction of orthodontic tooth movement (OTM) following periodontal regenerative surgery influences clinical and radiographic outcomes in periodontitis patients and to identify factors associated with regenerative outcomes. Methods Thirty-six patients with 130 infrabony defects treated with regenerative therapy were included. Defects were categorized according to subsequent OTM direction: away from the defect (Away-From-Defect group; n = 68) or into the defect (Into-Defect group; n = 62). Radiographic infrabony defect depth (IBD), probing pocket depth (PPD), and clinical attachment loss (CAL) were assessed at 1 and 2 years post-surgery. Factors associated with 2-year IBD reduction were evaluated using multivariable linear mixed-effects models. Results At 1 and 2 years, mean radiographic IBD reduction was 3.13 ± 0.99 mm and 3.12 ± 1.02 mm in the Away-From-Defect group, and 3.05 ± 0.92 mm and 2.97 ± 0.93 mm in the Into-Defect group, respectively. Both groups demonstrated significant radiographic and clinical improvements compared with baseline ( p < .001), with no significant inter-group differences detected ( p > .05). Multivariable analyses identified baseline defect depth, defect morphology, and furcation involvement as significant factors associated with IBD reduction. Conclusion OTM direction following regenerative surgery was not significantly associated with 2-year clinical or radiographic outcomes in this retrospective cohort. Baseline defect depth, defect morphology, and furcation involvement were associated with regenerative outcomes. These findings suggest that OTM into regenerated infrabony defects may be clinically feasible when periodontal health is well maintained, although a clinically meaningful effect of OTM direction cannot be excluded. Clinical Relevance Comparable periodontal regenerative outcomes following OTM toward regenerated infrabony defects provide clinical evidence to guide orthodontic treatment planning after periodontal regeneration in periodontally stable patients.